"You talk of compromises, but what exactly is her husband doing on that score? He could go into the bedroom at the end of the day and shut the door but won't. He could go into the office a couple of days a week but won't. He doesn't have to WFH but selfishly does even though he knows they don't have the space for it and it's causing both inconvenience and distress for his family. He won't meet her halfway, yet she's expected to accommodate him?*
No. She's not expected to accommodate him. Clearly if he was in the office, she could just let the toddler run around and shout. But here's the fact of the matter.
What he should be doing, is a fine story. It's not what he is doing. Go to the office? Between the two of these adults, (despite numerous people saying it's the first and obvious step to take) they can't even manage for him to work somewhere in the flat with a door closed! ("he won't/you can still hear his voice/the child will scream anyway")
So the actual, practical thing to do, is not keep harping on about how he needs to go to an office when it's not going to happen. Hence people are telling OP things to try if this is situation she has to face. Not saying it's right or wrong. But it's the situation. You can either whine eternal about how unfair you find it, which changes nothing, or you can try and make improvements.
However, you are faced with two adults who can't even contemplate doing an earlier bath time, or moving out of sight behind a closed door, to make a situation easier, then complain about how difficult everything is.
I wonder when the child goes to bed? If he starts nursery at 7.30 he must be up around 6.30. He doesn't get home until 4.30. Is he not knackered and ready for bed fairly early?